The present invention is directed to a variable capacitor, and more specifically to a variable capacitor and method in which pressurally engaged plates separated by a low friction dielectric are rotated relative to one another to vary capacitance.
Some radio frequency (RF) turning functions cannot be performed by conventional electronic turning devices due to the large voltages and currents that may be present under some operating conditions, such as during certain impedance transformations. Capacitors available for use in RF devices that operate under such conditions include capacitors with multiple spaced apart electrically conductive plates that are rotated relative to another set of such plates interleaved with the first set to vary capacitance. The dielectric between adjacent plates is typically air to reduce friction. Because of the dielectric properties of air, the number of plates and the space between the plates can be relatively large. Thus, such variable capacitors can be expensive and consume relatively large amounts of space.
Accordingly, it is an object of the present invention to provide a novel variable capacitor and method that obviates the problems of the prior art.
It is further object of the present invention to provide a novel variable capacitor and method in which the number of plates and the space between the plates is reduced from that needed for air dielectric variable capacitors.
It is still a further object of the present invention provide a novel variable capacitor and method in which two plates pressurally engage a disk of low friction dielectric therebetween to reduce space and cost.
It is yet a further object of the present invention to provide a novel variable capacitor and method in which a Teflon.TM. disk separates two pressurally-engaged, rotatable circuit boards, each with a thin pattern of electrically conductive material thereon.
It is another object of the present invention to provide a novel variable capacitor and method in which two pressurally engaged, rotatable plates are circuit boards that have two semicircular patterns thereon, one that is electrically connected to the capacitor and one that is not, the two patterns keeping the plates a predetermined distance from a low friction dielectric therebetween.
It is yet another object of the present invention to provide a novel method of varying capacitance in which plates compress a Teflon.TM. dielectric disk therebetween and in which the friction between the plates and the disk allows the plates to be rotated relative to one another to vary capacitance.
These and many other objects and advantages of the present invention will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims, the appended drawings, and the following detailed description of the preferred embodiments.